9 replies to this topic

[RedzoneMN]

I’m constructing a concrete pier 14 inches in diameter. The concrete is to be poured tomorrow. What is the best way to ensure that there are no voids around the j bolts.. Currently the bolts are in a wooden template which I will place into the concrete. Will moving the bolts and the template up and down a few times ensure that the concrete flows around the bolts. I don’t think there is enough room around the template to use any vibration. I suppose I could use a rebar and push it up and down a few times.

Edited by RedzoneMN, 12 August 2024 - 07:19 AM.

[Couder]

I put mine on 1" wide boards hooked together (kind of like a tic-tac-toe start), so I could pour right over/through them. Too much movement of them and you tend to get the rocks displaced and have none close to the bars.

[Overtime]

Something like this? https://www.harborfr...ator-34923.html

[KTAZ]

Something like this? https://www.harborfr...ator-34923.html

Complete overkill. Vibrating concrete can lead to poor results if you are not skilled in doing it.

 

As you stated, simply move the template up and down a few times near the end of the travel and the concrete will settle in around your J bolts just fine.

Edited by KTAZ, 12 August 2024 - 09:50 AM.

[DSOGabe]

As others posted, just jiggle the template up and down a bit. Can also do it in a slight circular motion to get the concrete to settle in around the bolts as well as below and above them. 

Just make sure that the template's alignment to north is not compromised. 

When I poured my pier, that is the technique is used. Pushed the template down with a little rotation to just below the height I wanted then slowly raised it up then down again a few times. Finally set a couple of 2x4 studs to hold it at the height I wanted. 

[Inkie]

Complete overkill. Vibrating concrete can lead to poor results if you are not skilled in doing it.

 

As you stated, simply move the template up and down a few times near the end of the travel and the concrete will settle in around your J bolts just fine.

This.  It's what I did.  VERY....VERY...careful about the MDF template with holes and the bolts tightened up in each hole.  Measure five times, drill once, and then measure and re-tighten each bolt to ensure their centers are spaced correctly, across and diagonally.  Holes are a little enlarged for this purpose.

 

Then, pour concrete in to the top. Work it a bit with a rod to help it to fill up the tube/form properly, then set the template atop the leveled off concrete.  Slightly twist it left and right just two-three degrees, and up and down just an inch, no more!  Then, slowly lower it until it contacts the lip of the tube.  

[Broz22]

I put an ~ 6" diameter hole in the top of my template. I poured the concrete to just below the bottom of where the j-bolts would be, then put the template with the j-bolts on top of a section of 12" sonotube set onto the poured concrete, then troweled the rest of the concrete through the hole in the center of the template. Seemed to work well using fairly plastic (neither too wet or too dry) concrete for the top section. Oh, and I had rebar  overlapping the j-bolts by ~ 6" and wire tied them through the hole prior to adding the top section of concrete. All seems solid  and the pier was well aligned (within ~ 1 degree - close enough for the mount azimuth adjustment range).

John

[Shelly n Mike]

I made a 12 inch pier with a menards round form like a sono tube but $15.  For the j bolts I got a 12x12 inch 1/4 inch clear plexiglass from Amazon.  That way when the bolts are sunk in, lifted up and down a bit then settled on the tube I could see the concrete under it to be sure it was all even.

 

Don't forget to keep the alignment board to make holes for the pier screwed on top.  Then set aside for another pier in the future if needed.

[peculiar_polar_ring]

I don't know if my way is any better, but when I poured mine, I vibrated the form on the edges with a sawzall and it set the concrete well. Be sure you don't vibrate it too long though

[speedster]

sawzall is brilliant